1. Field of the Invention
This invention relates to fluid spreading devices and more particularly to a vehicle carried fluid spreader apparatus having multiple spray bars at least one of which is swingingly movable about a single angularly disposed axis between extended and stowed positions.
2. Description of the Prior Art
In the spreading of fluids, such as hot asphalt on roadways, a tank truck is often used, with the truck having a substantially fixed centrally located spray bar extending across the rear of the truck.
Due to Federal and regional laws, the legal width of a highway operated motor vehicle is limited, and this sets the maximum length of the fixed centrally located spray bar. To increase the fluid spray path beyond that which can be achieved by the fixed centrally located spray bar, a pair of extender spray bars are often mounted on the opposite ends of the fixed spray bar, and those extender spray bars are movable between extended and stowed positions. In addition to conforming to the legal width restrictions, the extender spray bars must be movable so as to avoid damage to the extender spray bars and/or to any obstructions that may, and oftentimes are, encountered during the operation of such spraying equipment.
When spreading fluid materials such as hot asphalt, it is advantageous to provide for recirculation of the fluid through the spray bars and back to the fluid supply tank to maintain the molten state of the fluid when the apparatus is not spreading the fluid, such as when the truck is being driven to or between job sites, refilling of the supply tank, and other standby operating modes. Explaining further, when hot asphalt is being applied, it is heated in the tank of the truck and pumped to the spray bars. If the hot asphalt cools in the spray bars during a standby operating mode, it will become less fluid and will clog the apparatus. When this occurs, a very messy and time consuming clean-up operation must be accomplished, which usually involves circulatingly flushing the entire system with a suitable solvent.
A particular prior art device is fully disclosed in U.S. Pat. No. 3,838,817, issued on Oct. 4, 1974 to the same inventor. Briefly, this prior art device includes an elongated substantially fixed, i.e., non-swinging, spray bar carried transversely on the back of a spreader tank truck with extender spray bars movably mounted on the opposite ends thereof by swing joints. Each of the extender spray bars is mounted on a double swing joint arrangement so that it is movable about both a horizontal axis and a vertical axis to accomplish the desired movement between the extended and stowed positions. The swing joints and the spray bars are provided with dual fluid flow paths so that the fluid delivered under pressure from the supply tank may be serially and recirculatingly supplied to the spray bars and returned to the supply tank to maintain the molten state of the fluids during standby operating modes. The fixed spray bar and the extender spray bars are provided with spacedly arranged nozzles for sprayingly applying the fluids and the nozzles are controlled by suitable linear actuators. The nozzles in the fixed spray bar are ganged for simultaneous operation and are controlled by a linear actuator, and the nozzles in the extender spray bars are similarly ganged and under the control of separate linear actuators. In this manner, the nozzles in the fixed spray bar and the nozzles in the extender spray bars may be independently or simultaneously operated.
The normal fluid flow path in this prior art structure is such that the fluid is directed through the extender spray bar to the fixed spray bar. However, the apparatus is provided with means whereby the fluid is concurrently supplied to the extender spray bar and fixed spray bar to insure that a sufficient quantity of the fluid is supplied directly to the fixed spray bar during the operating mode of the apparatus.
The above described prior art device is a substantial improvement in the art, however, a few shortcomings and drawbacks exist in that apparatus. In the first place, the double swing joint arrangement for mounting of the extender spray bars are very costly and rather bulky devices. And, the dual fluid flow passages formed in those multiple swing joints and the associated conduits thereof are quite long and this dual passage length contributes to the cooling and solidification tendencies of the fluid materials. Another drawback of this particular prior art device concerns the ganged interconnection of the fluid spray nozzles. The ganged nozzles must be so arranged that they open and close simultaneously under the control of the linear actuator, and this involves a rather complex and time consuming precision adjustment procedure to insure that no leakage occurs when the nozzles are in the closed position.
Therefore, a need exists for a new and improved fluid spreading apparatus which overcomes some of the shortcomings of the prior art.